Band-structure calculation of MBe₁₃ (M=La, Ce, Th and U)

The one-electron energy band structures for LaBe₁₃, CeBe₁₃, ThBe₁₃ and UBe₁₃ were calculated by the self-consistent APW method with the local density approximation. It was found that the Be s(p) bands form wide valence bands below a pseudogap at 0.8 eV below the Fermi energy E_F in UBe₁₃; and the Be p bands extend mostly above a pseudogap at 1.9 eV above E_F in UBe₁₃. Between these bands, there are M d-Be p mixed bands. In CeBe₁₃ and UBe₁₃, the f bands are inserted among the d-p mixed bands. Due to the squeezing effect of the p-f mixings from both above and below the f bands, the f band widths in CeBe₁₃ and UBe₁₃ are very small, only 1 eV in UBe₁₃, much narrower than the experimentally observed PES-BIS peak, indicating the importance of the many-body effect. In LaBe₁₃ and ThBe₁₃, the f band widths are much larger, more than twice that in UBe₁₃, due to the reversed p-f mixing effect. The p-f mixing parameters for these materials were also evaluated from the present band calculation.